Fe-si-ti composition or product and process of preparing same



March 17, 1959 AND LD 0 PRODUCT PROCESS OF PREPARING SAME M. F. BEC COMPOSITI Fe Si -Ti INVENTOR flflx E Eat/V7040,

- ATTORNEY Unit d ate .Pe sflfl Fe-Si-Ti COMPOSITION OR PRODUCT AND n PROCESSOF PREPARING SAME Max F. Bechtold, Kennett Square, Pa., assignorto E. I du Pont de Nemours and Company, Wilmington, Deb, corporation o e awa j .H

Application April 17, 1958, Serial No. 729,157 .14 Claim s'. (or. "ls-.5

This invention relates to powder metallurgy compositions and to shaped objects of alloys having high heat and oxidation resistance.v More particularly, this invention relates to new iron-silicon-titanium powder compositions, to shaped objects of iron-silic'on-titanium alloys that are hard, strong, creep-resistant and resistant to. oxidation at high temperature, and to methods for preparing such shaped objects.

-Considerable effort has been expended in the search for metals or alloys that are resistant to attack by acids and alkalies and that can be subjected to high temperatures in air without deleterious effects, such as loss of strength, warpage or oxidation. Although metallic compositions showing some of these advantageous properties have been made, they are usually difficult to obtain in the form of shaped objects, are usually quite expensive, and domestic sources for the metals involvedare often not adequate for normal needs. In addition to the need for strong metallic structures .having high heatand oxidation resistance, low density compositions resistant to abrasion are also desired.

It is an object of this invention to provide novel powder metallurgy compositions. A further object is to provide novel iron-silicon-titanium powder compositions. A still further object is to provide shaped objects of ironsilicon-titanium alloys that are hard,:strong, creep-resistant and resistant to oxidation at high temperatures. Another object is to provide a novel method for prepar-. ing the aforesaid shaped objects. Still another object is to provide shaped articles of iron-silicon-titanium metallic structures of low density and which are resistant to abrasion in addition to having high heat and oxidation resistance. Other objects will appear hereinafter.

These and other objects of this invention are accomplished by providing a powder metallurgy composition consisting of a powder having substantially all particles, i., e., at least 95% (by weight), less than 75 microns insize and consisting essentially of iron, silicon and titanium in the proportions of 20-45% iron, 25-45%- silicon and 25-47.5% titanium. Preferredcompositions are those having an average particle size below about 60 microns with at least 2 5% (by weight) of the particles being less than 45 microns in size.

The drawing 'is a three-component diagram of Fe-Si-Ti alloy compositions in weight percent.

The area within the polygon ABCDEF embraces the. novel 'Fe--Si-Ti alloy compositions of this invention consisting essentiallyof -45% Fe, -45% .Si, and 25-47596. Ti. I

2,878,113 erase. Msa1 5a.

- 2 The area within the polygon A'B'C'D'E'F' embraces the. preferred alloy compositions of this invention consisting essentiallyof 2040% Fe, 27.5-42.5% Si, and 45% Ti. v

The area within the polygon abcdej embraces particuuarly preferred alloy compositions of this invention consisting essentially sisting essentially of 22;5-35% Fe, 3040% Si, and -45% Ti..: J

t "The area within the polygonab'c'zie'f embraces the most preferred alloy compositionszofthis invention conof 225-3095 Fe,'30-'37.5% Si' and. 35-45%Ti.-'I-

Strong metallic objects resistant to oxidation, high temperatures and abrasion are prepared by pressing these powders in the form of the desired object and then heating rapidly to a temperature of at least 900 C., or by hot-pressing. Such objects are also part of this invention. For increased oxidation resistance and high temperature strength, compositions containing 20-40% Fe, 27.5-42.5% Si and 30-45% Tiare preferred, while.

: compositions in the range of 22.,535% Fe, 30-40% Si compounds,suc'h as Fesi Tig and 35-45% Ti possess these properties to a still greater extent. Compositions with maximum melting point and other desirable properties contain 22.5-30% Fe, 30- 37.5% Si and 35-45% Ti, and include, for example, compositions of the following atom'ratios:

and 2Fe5Si-3Ti. 'The X-ray diffraction patterns of thesemost preferred alloy compositions, after heating rapidly to a temperature of "at least 900C. or hot pressing, show them to be substantially free of the elements Fe, Si, Ti, their known binary compounds and their reaction products with the atmosphere. These alloys are thought to be composed of new ternary metal silicide' Particularly useful compositions for" the production of shaped objects are obtained bygrinding together ferrotitanium and silicotitanium in such proportions that the resulting powder falls within the ranges of composition and particle size described above, Such composi tions are readily shaped by cold-pressing and converted to alloy objects by heating to'a temperature of 1100-, 1400" C. within a short period of time, c. g., .a few, seconds to 10 minutes. Alloy objects are also obtained by hot-pressingthe powders at 2000-6000 p. s. i. and

I proportions of Ti likewise lead to softer, less refractory"- alloys, while increasing proportions-of Si result in more brittle, lower melting products.

The following examples illustrate the preparation and.

properties of the compositions. and derived shaped objectsof this invention.

EXAMPLE I n I Coarse chunks (35.863.) for}; commercial ferrosilicon alloy (22.02% Si, the-remainderbeingsubstantially all.

. 3 Fe) were ball-milled in a one-quart porcelain ball mill for 66 hours with 52 g. of TiSi powder to yield a mixed fine powder with input ratio (Fe-Si-Ti) of 31.80-40.92- 27.28 by weight. Approximately 2 g. of this powder was pressed at 40 tons per square inch (t. s. i.) pressure in a cylindrical steel die to yield a green pellet. This pellet was placed for two minutes inside a muffle furnace operating in air at 1360?. C. After removal from the Reduced iron powder (61 g.) and silicotitanium alloy, (98.3 g.) (analysis: Fe, 1.05%; Si, 44.83%; Ti, 45.10%; others, 902%) about 20 mesh in size were-ball-milled for 22-hours inaporcelain'hall mill to'yield'a fine powder 7 having an input ratio (Fe-Si-Ti) of 43.49-28.17-28.34. A 25 g. sample of this powder was mixed with 4.9' g. of 15% aqueous NaOH, and dried. A green bar prepared from this powder was fired as in Example III. It attained 1300C. in 19 seconds and reached a maximum temperature higher than 1300 C. in 22 seconds. The product was hard, strong and metallic. The following table shows weight and dimensional changes:

furnace and cooling, the pellet was found to be strong, metallic in appearance, harder than glass and substan- 10 Weight Thick- Width Length tially unoxidized on the surface. It was not responsive 53?? 1 (cm) (cm-J to a magnet, indicating that reaction had occurred during firing, since the input ferrosilicon and the unfired Green J96 M178 M437 3'85 pellet were responslveto a magnet. Fired 11.261 0.5511 1.1000 3.20

5 p A section of this bar was heat-treated in air as 1n Exam- The ball-m lled powder of Example} was. pressed at. PIG In with the f ll i results; 13. t. s. 1. in a rectangular steel. d1e. (nominal size 1%" x A." with rounded corners) to yield a green Mm 16h l 1 bar, which was fired. for minutes. in air at. 1 360 C. Initial r rssumssvoya The weight and dimensions before and after firing were: 0. Q CI CI Weight "rmek- Width Length i Bulk Weight (g.) 2.1801 2.1000 2.1974 2.100s 2.1008 (g.) 1 near; (0111.)? 1 (0111.): Density Thickness cm.) i 0.6422 0.6598 0.6563 0.6542 1 0.6548 (0111.). Jee) g5 Wldth(cm. 0.5455 0.05 0.0503 0. 0597 0. 0037 Length (cm.) 1.1000 1.1945 1.2050 1.2000 1.2000 Green 10. 405 0. 6035 T 1 2:114 ass 3.2a V Fired 10-570 3 3- After the initial heat at 1000 C., the bar showed substantial stability in weight and dimensions and at the The resultant porous, hard, metallic bar. withstood. dropem! 0f the test was Very d and metalll'c' ping on a. hard floor without. fracture and. when heated EXAMPLE v successively at 1000, I100", I200 and1300 C. in air. Ferrotitanium y lumps 4 g analyfly Fe (16 hours at each. temperature, with coolingand weigh- V f 1 ing before and after each heat) stabilized in weight at 657%?51, 3 004%) 1100 C. The total weight gain. during the 1200" and were fl s i t .slllmmamun? alloy 13005 heats was y 0 of Example IV toyield a fine powder (mput ratio: 25.44 1 Fe-3-2.70 Si-41L86 Ti). A; bar was pressed and fired, EXAMPLE III I in Example III. It attained 1 300 C. within 24 seconds Reduced. iron powder (7.8 g.) was ball-milled for 48 and a m Fm above 13000 hours in a porcelain ball mill. with. TiSi, powder (10.4 g.) 40 0nd? After Qooll ng the bar was hard, porous, sound, to i l a fi e i powdu with input ratio p s -n metallic and substantially undistorted. It survived reof 41 540324 31 Was Prepared peated drops of 12 feet to a hard floor without fracture. fi d 2 minutes in air at 0 C It attained 13000 C The; following weight and dimensional changes occurred within 15. seconds and exceeded this. temperature within 18 during firing: seconds (exhibiting calorescence"). The following re- 45 g v sultsshow weight. and dimensional changes on firing: Weight Thick- W h 1 Length B (g.) ness (0111.) (0111.) Density -l 1 (tr-i Weight Thick- Width Length 1 1 1 (2- 7 new (0111-): -1 Graenbar 11. 033 0.1033 1.2374 3.35 I 3.22 (cm) Fired bar 12.113 1 0.1861, 1.2218 3.80 ass 3.13%.; g ggg 3:23 The following. changes occurred on successive" heat-treatments in. air. of a section of this bar:

A hard metallic bar was obtained by the firing. A section of this bar was weighed. and. measured before and mum f ifihrs'sucwsslvely after heating at a series, of temperatures with results as o a n a follows: 1.000 "0. 1,100 o. 1,200 (1. 1 500 0.

1 Weight (g.) 2. 2150. 2.31141. 2.3000 2.3590 2.3000 fAfter 16111-5, successively at- Thickness 0111)--.. 0.6388 016450 0.6424: 1 0.0438 0.0445 Initial Width (cm. 0.7702 1 0. 7810 0.1100 0.7715 0.7705 1 Len thtcm.) 1.4442 3 1.4112 1 .4500 1.4500 1. 4500 Z2675 22m 228m Thus, the alloy showed considerable stability after the 3.5 31 1; 3.231 1; 312 6 1000" (2'. heat. 113558 113021 133628 0 EXAMPLE VI Titanium disilicide powder g.) and steel powder The sample was essentially all hardmetal atthe end 8-) y Others. of the-heat treatments-. 1 ball-milled to yield a fine rnixedpowder (input ratio: v 7 7 32.49 l e-36.46 Si-31.05 Ti). Two portions of this powutes in a graphite mold; In (27), 1300- 61 was; reached Within 30 seconds and a maximum temperature above" this in 38' secondsf The'follow B m it HafdliessKlgoop) at various physical properties are shown in Table B while,

I1 0703 y 03 s Test 2, 7 .3 (percemy v 5 the results of oxidation tests are shown in Table C.

10 g. 100 g. 1,000 Table A 4.29 10.5 1305 I 879 -722 4J8 Q63 1:948 1,222 1,052 16 'l l egt Raw Materials Input floniposgtiltligsI e-si Ti Al The eifect of heat-treatment in air on these objects :is {l fgg gg gi g gf -ggf'g lg gg hg( .96

shown in the following table: v

. Changes (11; Object; Changei n Object. a After-"16 houzs successively Weight Dimen- Weight Dimen- (percent) 'sion 2 (percent) sion (percent) (percent) 1 Total accumulated growth based on initial size and weight. 1 Average of three dimensions.

p 7 EXAMPLE VII In the following tests, the ingredients (Table A) were mixed by dry ball mi1ling(about hours) until 'a'dequat e particle size reduction was obtained. A typical screen analysis after ball milling was thatshown in Test No.;5- a's followsz' Screen Particle By weight, Size Size Percent Mesh n=Mlcrons The resultant powders were placed in a graphite mold Slllcotitanium. g -zggg sii eg s Ti) rgtTgkm Iron powder..- 7i J eluded with others (27.66 Fe- {Smcomamuml 36.06 Si-36.28 Ti) ratio. Ferrotitauium 23.84 30.65- 39.24 0.42 5.85 (25.44 lilicotsltlaiuii1m Fe-32.70 Si41.86 Ti) ratio.

30 86-33 10-34 -0 55-0 64(31 23 Titanium--- {Titanium-dismal Fe 33.50 si 35.27 Ti) ratio. {Iron }22.53 39.57 36.02 0.87 1.01 (2296 Titanium disilicide Fe-40.33 Si36.71 Ti) ratio. m 25.70 -33.e2-33.s3- -6.76 (Al ineluded with others) (27.66 Fe- 36.06 S136.28 Ti) ratio.

25 Table B.-Physzcal properties of products Transverse Rupture Knoop Mold (p. s. 1., 1 span) Bulk Hardness Test N 0. Temp. Density g. C.) (g./cc load) 30 1,000 0. 1,100 O.

cooled. Thebars were descaled by grinding off any graphite adhesions or surface oxidation products and were cut or ground into physical test specimens. Valuesfor ln tests number 1 to 5 the mold pressure was 4000 as 000 p. s. i.

The, transverse rupture strength was also determined Table C.--Oxz'dation tests, percent growth in air 16 hours' at 'each' temperature (cumulative) Test No.

Wt. Dimen- Wt. Dimen- Wt. Dimen- Wt. Dimen- Wt. Dimen- Wt. Dimension sion 4 sion sion sion sion .07 ..19.. .14 .41 .25 1.06 3.41 1.08 5.44 Melted .67 .96 1.38 1.94 2.81 V 4.25 14.95 26.23 .14 .34 .26 .58 .39 .82 .65 1.65 .91 3.76 Melted .49 .78 .63 1.05 -.65 1.25 .84 1.84 1.43 7.52 24 62 54 1. l6 83 1. 63 1.05 2. 69 1. 40 4. 25

-Strong metal; surface 1- used (,TabIe'B) was applied. The mold was heated by induction to the temperature indicated in Table B. This required 24 to 89 minutes, depending on the size of the mold and-molded object. The final pressure was apeacti'on 'with" refractory support.

' A sample of the alloy test No. 6 had a tensile-strength 70 and times as follows before fracture (without measurable plied as the assembly attained about 1100 C. The pres- T sure and teri'iperature indicated were held for 2 to 10 minutes. depending on' the progress of consolidation as shown by diminishing volume of the moldedobject. The

elongation) 'Iemp.Held(Hrs.)- 19.63 1.37 21.3 0.35 4.75. Temp. C.) 820 820-915 915 915-1000 1,000

' p; .s. i. and in tests number 6 and 7 the mold pressure Total Percent Test No.

Although the new products of this invention are composed essentially of iron, silicon and titanium, up to 15%,, preferably less than 10%, of other metals andinert diluents that do not materially affect the basic and novel; characteristics of the compositions and alloys can bepres ent. Examples are the impurities usually. found in minor amount in ferrosilicon, ferrotitanium orsilicotitaniumt 211-. loys such as Al, C, Ca, Mn and Cr, and metal oxides from attrition ofporcelain ball mills. n is reterred that the r vamat s. c n. as mal emu ate Qt: impurities, particularly C, as possible.

The final alloys or shaped objects of this inventiondo n contain p r i le am s f. e e e ron. ili? con or titanium although these may constitute a considerable part of the powder metallurgy compositions beforfl firing or hot-pressing. This is very desirable. since iron, and titanium are generally not stable to high temperature oxidation and elemental silicon is brittle. Some oxidation of the newalloys, particularly the porous alloys, may occur on prolonged heating at high temperature However,

oxidation is not extensive as shown by the small weight gains recorded in the examples and doesnot materially. weaken the. structure. In such products comple x qxiglgs q f iron, silicon and titanium may be present; in minor amount. For ease of understanding andsimplicity th e compositions listed are those of the initial components, before prolonged heating in air.

In preparing the powder compositions; of this, invert, im s am ntal' m S ic n an t n m and/q he r: binary alloys may be employed. The iron is gene; pre-alloyed with silicon whiletitanium may be pregaligyed with iron or with silicon. Large amounts offunalloy'ed, elements, particularly silicon and titanium, in the start ng; materials cause mechanical defects, such as bubbleaand;

cracks and adhesion to mold surfaces during the; process, 4:5

of conversion to hard compositions. The elements in" controlled proportions, however, are sometimes useful in; obtaining alloys which can be fired at thelowest possiblel, initiation temperatures.

P ra ly. ese owde met llurg qpmaq iti nas az sist of an intimate mixture of silicotitanium, or titanium, disilicide with iron or with ferrosilicon. Suitable powd ers, are readily obtained by milling or dry-grinding by con; ventional methods until the desired particle size is achieved. The progress of the grinding or rnillingmay be followed by usual microscopic techniques. Although such powders may contairrup to 5% by weight of-rparti} cles coarser than 75 microns and shaped objectssatis factory for some purposes can be prepared therefrom, it is preferred that less than. 2% of such coarse grains be present, i. e., at least 98% by weight of all particlesare less than 75 microns. It is still better to screen out'all; coarse particles, since they serve as points of. chemical; and mechanical inhomogeneities. Although powders having an average particlesize below about 60 microns with at least 25%(by weight) oftheparticles less than 45. microns in size are preferred, satisfactory shaped alloy/i objects can be prepared from powders ofparticle size range 45 to 75 microns and from powders of size range 1 to 45 microns. commercial sources with a primary particle size of about- 1 micron, and commercial ferrosilicons, ferrotitaniums and silicotitaniums which are usuallymuchcoarserte. g 8 -200 mesh) are suitable for use in preparing the ed111p6 sitions of this invention.

arr sewa e. arena-rest as. bn an. be shar d; bu compacting or pressing the powdepinto. the. form. desired; r by sl nrqas ng and. d x ns- M x ur s w ic c nta n.

water'qr other .qljatile liquids should be dried before heattreatment to, a liquid, content 0f less than about 3% to least 900 C. and preferably 1l00-1400 C. The maximum temperaturqwhich maybe employedis thatatwhichtheresultantalloy losesitsgdimensional stability. In some as hig emp ra is h a s .00 Thawi: mum temperaturedepends; upon the exact composition of' each; powdercompact, the, propertiesdesired, and the .heating. method, and maybe readily determined by preliminary experiments.

The conyersion, of" the powder composition to solid al loy, generallwinvolyes calorescence (i. e., an exothermiq, reaction characterized" by an-increase in temperature as evidenced by anincrease inluminosity) that is induced when a considerable portionof the; shapedobject is heated to a temperature of at least 900 C. The internal temperature of the shaped object during conversion is generally 11. 00.41 .0 C, Whe he; spfintanflous heat i crease is; low, the; temperature of: the; exte nally pplied Ironpowder, which is available from; 79"

heat-must be higher, S mn mndln as=tia1= mass. of iicc n t h s conv rsi n involve heating the shaped powder object withwamoxygen. gas torch or placing the object in a hot furnace. When the starting powders are selected from the preferred compositions, the cqnyersion step proceeds readily with minimum weight change, small. and predictable dimensional changes, andlittle deformation ofthe shaped object. To obtain optimum; properties in the resulting alloy,

it is preferred that "the heating I in air berapid However,

if the green compact containsmoisture the initial rate of heating, i. e., up to-about 350f"C., must be slow to permit drying without; cracking, After a temperature of about 350 C. is reached, heating'totheinitiationtemperature Q abm t 9.0. o ldh s ap spossibl im slow heating in this rangebrings about-powdering, expansion, and. cracking of the shaped object before conuer ion, The, time required will depend upon the size ofythepbject being fired; however, for small objects the p eat n 119.1 .11. e. accomplished. n, at mo 1 i ut s (Tables D and E); illustratethis fact.

Table. D

Ingredients Input Composition Fe-Sl-Tt-Al-Others mam- TabI'e -D-Continued f 'lesl: Ingredients Input Composition No. .Fe-Bi-Ti-Al-Others fstelpowder 4s.1s-21.oa-2a.02- -1.72' (Al in- 6 was... s.n..m...... g gggsg gsp 44.ae-21.9s-ao.e-2.4e-o.92 (45.91M- 22.73Si31.36Ti) ratio.

' Titanium powder. 20.4923.83-47.613.00-5.07(22.29Fe a i i8 i$liu$:::::::i I anum powderz1.4e-1s.27-4s.s4-4.os-ae5 29.76M- i 17.63Sl-52.61Ti) ratio.

ron powder Ferrosmcon sum-2s.37-19.s5-o.4s-1.2a (sameigfi i msngnde 2s.ses1-2o.2o'r1 ratio.

- an um pow er n 21.9s-1s.p2-eo.o-a.s1-0.s2 (newne- {Tmnmm msmcme" 14.25S162.78Tl) ratio. 12 }57.74-.21.59-19.65-0.47-0.55.(58.34Fe

zrsisi-iess'rnmnm 13 41.3120.0534.13.48-1.06 43.27%-

----- 21.00Si-35.73Ti) ratio. 5 lron Powder- I 39.36-37.91-18.04-0.47-4.22(41.30Fe- 'ig ggggygg 39.77Bl-18.93Tl)18tl0.

In Table E the abbreviations CP, AF, HP, AW, AD and T. R. are employed with the following meaning:

CP, AF=cold-pressed, air-fired at temperature C.) shown.

HP=hot-pressed at temperature and pressure shown C./p. s. i.).

AW=weight change and AD=dimensional change in the stated temperature range on heating as in Example III.

T. R.=transverse rupture strength (p. s. i.) at temperature C.) shown.

Table E Bulk Knoop Test Fabrication Density Hardness Property Deficiency No. (el e) (100 2- Load) 1 CRAB 1,200-.. 4.65 Melts below 1,300.

2 GP,AF 1,100--- 4.37 Exudes metal below 1,300". AW=20.5%, 1,0001,200.

3 HP 1,200/4,000... 5.10 1,219 Exudes metal at 1,200".

4 CP,AF1,100 4.86 929 Swells at 1,200". Ex udes metal at 1,300.

6 CP,AF 1,000--- 3.80 AW=24% ,000- 1,100. Severe scalmg.

6 HP1,150/4,000-- 4.47 Wtiaolg, T.R. 6,660 at 7 HP 1,205/4,000.-. 5,26 1,437 AD =7.8 2% at 1,000-

1,200". AW==11.25% at 1,000-1,300.

8-..-.. HP 1,200/4,000.-- 3.87 1,123 AV1V;]%. 72% at 1,000-

9 HP 1,250/4,000.-. 4.01 974 AVlV -1=E%j7% at 1,000-

10 HP1,300/4,000--. 5.13 1511531107572, at 1,000-

11 HP 1,180/4,000..- 4.04 Avil %25.ll4% at 1,000-- 12- HP 1,130 3,000... 5.14 Weak. T.R. 10,758 at 4,100. AW==8.91%.

at LOUD-1,300".

13 HP 1,200/3,000" 4.98 Spelling at 1,100.

14 HP 1,200/3,000.-. 4.70 1,266 AW=7.04%. AD:-

The new alloys of this invention are hard, resistant. to thermal shock and to degradation by heat and oxygen. In fact, heat-treatment of the alloys strengthens and hardcns them. Such properties are surprising since some of the alloys have a high percentage of pores of extremely small size. Although upon heating in air at 800-l000' C. a small weight increase takes place, little further increase is noted at temperatures of 1l00-1200 C. Thus, these alloy compositions undergo less than a gain. or loss (by exudation, for example) in weight and less than 5% change in linear dimensions on heat-treatment in for l6 hours each at 1000"", 11"00 and "1200 CI The preferred alloys show lessthan 1% weight change and less than 2% dimensional growth on similar heattreatment. The best alloys show less than 1.5% weight terials for fabricationof impact-resistant composite structures.v

, The properties of tion' I give them utility in diverse applications. Their thermal stability coupled with electrical resistance inthe range of conventional resistance wires and graphite renders them useful in the preparation of electric heating elements. 'Their hardness, indicated by ability to scratch glass, and ease of fabrication make them useful in the production oftools for cutting and sharpening operations.. They, alsofcan be fractured into grit size and used in the preparationjof bonded abrasive wheels and brazed'grit surfaces'o'n metal sheets.

The ease of fabrication of shaped objects is a particular advantage which may favor the use of these alloys over presently used refractories. The conversion to hard products takes place in air thereby avoiding the necessity for vacuum, inert, or reducing atmospheres and the products are easy to make in the form in which they are to be used, e. g., as structural components of high temperature furnaces and heat engines. Furthermore, the precursors of these alloys are commercially available from domestic non-strategic materials.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that this invention is not limited to the specific embodiments thereof except as defined in the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

I claim:

1. A powder metallurgy composition consisting of a powder having substantially all particles less than microns in size, and consisting essentially of iron, silicon and titanium in the proportions of 20-45% iron, 25-45% silicon and 25-47.5% titanium.

2. A powder metallurgy composition consisting of a powder having at least by weight of all particles less than 75 microns in size, and consisting essentially of iron, silicon and titanium in the proportions of 20- 40% iron, 27.5-42.5% silicon and 30-45% titanium.

3. A powder metallurgy composition consisting of a powder having at least 95% by weight of all particles less than 75 microns in size, and consisting essentially of iron, silicon and titanium in the proportions of 22.5-35% iron, 30-40% silicon and 35-45% titanium.

4. A powder metallurgy composition consisting of a powder having at least 95% by weight of all particles less than 75 microns in size, and consisting essentially of iron, silicon and titanium in the proportions of 22.530% iron, 30-37.5% silicon and 35-45% titanium.

5. A powder metallurgy composition consisting of a powder having an average particle size below about 60 microns with at least 25% by weight of the particles being less than 45 microns in size, and consisting essentially of iron, silicon and titanium in the proportions of 20-40% iron, 27.5-42.5% silicon and 30-45% titanium.

6. A powder metallurgy composition of an intimate mixture of ferrosilicon and silicotitanium metal powders having substantially all particles less than 75 microns in size, said intimate mixture of metal powders consisting essentially of iron, silicon and titanium in the proportions of 20-45% iron, 25-45% silicon and 25-47.5% titanium.

7. A powder metallurgy composition of an intimate the new compositions of this inven-" anemia new of iqr i en m and' ili e i iummet powde s having. substantially all part igles itiss than 75 UgliQl'QBS ti ons of 20-45% iron, 25-45% silicon and 25 41% titanium.

8. A powder metallurgy composition of, anintimate mixture of iron and titanium disilicide metal powders having substantially all particles less than 75 microns in size;

said intimate mixtureof metal powders consisting essentially of iron, silicon and titanium in the proportions oi 20-45% iron, 25-45% silicon and .25-47.5% titanium.

9. A shaped object having a minimum dimension of at 7 least 1mm. composed of an alloy consisting essentially of iron=,ilicon and titanium in the proportionslof 20-45% Y eta lur comp si on f. claim 3 and h tin sa d iron, 25-45% silicon, and 25-475?? titanium. 'iO. .A shaped object having a minimum dimension of atleast 1 mm; composed-of an'alloy consistingessentially of iron, silicon andtitenium in the proportions of 20-40% iron,.27.5-42.5% silicon and 30-45% titanium.

' IL A shaped object having a-minimum dimension oi tal powders c ns s ing at least 1 mm. composedof analloy consisting essentially I 1 2 of iron, silicon and. titanium "in the. proportions of 22.5- 35%' iron,"30-'40% silicon and 35-45% titanium.

12. Process for preparing a strong iron-silicon titanium object resistant to oxidation and high temperatures; which comprises p s ng inthe form. f 'saidgobject of the;

powder metallurgy composition of claim 1 and heating said composition to a temperature of-at least, 900 C.

13. Process for preparing a strongiron-silicon-titanium object resistant to oxidation and high temperatures which comprises pressing in the formof saidobject the powder metallurgy composition of claim 2 and heating said composition to a temperature of at least 900 C.

14. Process for preparing a strong iron-silicon-titanium object resistant to oxidation and high temperaturesrwhich comprises pressing in the form of said object the powder position toss temperature of at least 9 00-C;.

' v I I References Cited in the. file of this patent UNITED s ArEs PATENTS 2 323,988 Grant et al. Feb. 18, 1958 

1. A POWDER METALLURGY COMPOSITION CONSISTING OF A POWDER HAVING SUBSTANTIALLY ALL PARTICLES LESS THAN 75 MICRONS IN SIZE, AND CONSISTING ESSENTIALLY OF IRON, SILICON AND TITANIUM IN THE PROPORTIONS OF 20-45% IRON, 25-45% SILICON AND 25-47% TITANIUM. 